Variable ramp exhaust nozzle and clamshell reverser

ABSTRACT

Apparatus for varying the exhaust nozzle area and for reversing the thrust of an aircraft jet engine which is mounted on an aircraft wing so as to discharge the engine thrust flow through a D-shaped exhaust nozzle exit over the upper surface of the wing. For varying the exhaust nozzle area, a three segment ramp is lowered for increasing the exhaust exit area during takeoff and landing of the aircraft, and for the sound suppression mode. For thrust modulation and thrust reversing, the aft segment of the three segment ramp is rotated upwardly and forwardly from the ramp surface to a thrust flow deflecting position. Operating in combination therewith for thrust reversing is a curved or inverted U-shaped panel. For the thrust reversing mode, this curved or clamshell panel is pivoted rearwardly about a lower hinge line near the upper wing surface; thereby, exposing an opening in the upper duct wall through which the exhaust flow can be directed; provided, that the aft ramp segment is also rotated upwardly in abutment relation with the clamshell panel with the combination forming a clamshell blocker door arrangement. The safety feature being that the aft ramp segment or blocker panel in its raised position becomes highly loaded due to deflection of the exhaust flow; and through its interconnecting linkage arrangement with the aft swinging clamshell panel, any actuator or linkage failure would cause the blocker panel to swing down from the blocked flow position thereby permitting forward thrust flow.

United States Patent Stearns VARIABLE RAMP EXHAUST NOZZLE AND CLAMSHELLREVERSER [75] Inventor: Gabriel E. Stearns, Mercer Island,

Wash.

[73] Assignees: The Boeing Company, Seattle,

Wash.; Aeritalia S.p.A., Naples, Italy Filed: Apr. 18, 1974 Appl. No.:462,052

Related U.S. Application Data Division of Ser. No. 365,933, June 1,1973, Pat. No. 3,844,482.

U.S. Cl. 244/110 B; 239/265.37; 244/53 R Int. Cl. B64D 33/04 Field ofSearch... 244/53 R, 12 B, 23 B, 110 B,

[56] References Cited UNITED STATES PATENTS 2,620,622 12/1952 Lundberg239/265.37 2,979,893 4/l96l Meyer 239/265.29

Primary Examiner-Trygve M. Blix Assistant Examiner-Barry L. KelmachterAttorney, Agent, or FirmH. Gus Hartmann; Glenn Orlob; B. A. Donahue [57]ABSTRACT Apparatus for'varying the exhaust nozzle area and for Sept. 23,1975 reversing the thrust of an aircraft jet engine which is mounted onan aircraft wing so as to discharge the engine thrust flow through aD-shaped exhaust nozzle exit over the upper surface of the wing.

For varying the exhaust nozzle area, a three segment ramp is lowered forincreasing the exhaust exit area during takeoff and landing of theaircraft, and for the sound suppression mode.

For thrust modulation and thrust reversing, the aft segment of the threesegment ramp is rotated upwardly and forwardly from the ramp surface toa thrust flow deflecting position. Operating in combination therewithfor thrust reversing is a curved or inverted U-shaped panel, For thethrust reversing mode, this curved or clamshell panel is pivotedrearwardly about a lower hinge line near the upper wing surface;thereby, exposing an opening in the upper duct wall through which theexhaust flow can be directed; provided, that the aft ramp segment isalso rotated upwardly in abutment relation with the clamshell panel withthe combination forming a clamshell blocker door arrangement.

The safety feature being that the aft ramp segment or blocker panel inits raised position becomes highly loaded due to deflection of theexhaust flow; and through its interconnecting linkage arrangement withthe aft swinging clamshell panel, any actuator or linkage failure wouldcause the blocker panel to swing down from the blocked flow positionthereby permitting forward thrust flow.

4 Claims, 7 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of53,907,224

Sheet 2 of 5 3,907,224 4 US Patent Sept. 23,1975

US Patent Sept. 23,1975 Sheet 3 of5 3,907,224

Nw N

US Patent Sept. 23,1975 Sheet 4 of5 3,907,224

US Patent Sept. 23,1975 Sheet 5 of5 3,907,224

VARIABLE RAMP EXHAUST NOZZLE AND CLAMSIIELL REVERSER This is a divisionof application Ser. No. 365,933, filed June 1, 1973 now US. Pat. No.3,844,482.

SUMMARY OF THE INVENTION The invention relates to an apparatus forvarying the exhaust nozzle area and for reversing the thrust flow from ajet engine enclosed in a nacelle. The nacelle is mounted forward andabove on the wing of an aircraft and discarhges the discharges exhaustflow through a D-shaped nozzle exit and over the upper surface of thewing.

For varying the exhaust nozzle area, a variable ramp is utilized. Theramp is vertically adjustable and comprises three segments, which formthe lower surface of the D-shaped exhaust duct. The ramp extends fromwithin the duct to beyond the nozzle exit and provides for a smoothtransitional flow of the exhaust gases over the upper surface of thewing. At the slower aircraft speeds, such as for takeoff and landing,the ramp segments are positioned at their lower position for providingthe maximum exhaust nozzle area to attenuate the exhaust noise and toform the low speed exhaust nozzle for improved thrust efficiency. At thehigher aircraft cruise speeds, the ramp segments are raised to theirupper position to decrease the exhaust nozzle exit area for increasingthe thrust efficiency of the nozzle.

For reversing the thrust, a clamshell panel, which forms the aft upperportion of the exhaust nozzle, is pivoted downward to cooperate with anaft ramp segment that is swung upward against the clamshell panel andthereby forms a clamshell blocker door arrangement to block the exhaustflow and deflect it upward and forward over the nacelle and wing. Thisarrangement provides a much better turning surface geometry forincreasing the effectiveness of the thrust reversal.

One of the disadvantages of the conventional thrust reversing mechanismsis that if the elements of the reverser mechanism were to move due todrag forces caused by improper rigging of vibration loosening theconnections, they could go into reverse thrust with high power settingsin the engine and this could be disastrous. Whereas, in the presentinvention, the primary thrust reversing element is a blocker panel whichbecomes highly pressure loaded when in the thrust reversing positionsuch that the normal exhaust thrust flow will maintain it in the down orinoperative position in the event of a malfunction.

The fail safe mode or safety feature of the present invention is thatthe blocker panel, being the more highly loaded surface of the twoprimary parts making up the reversing means, will be forced to swingdown to an inoperative or neutral position and through itsinterconnecting linkage arrangement with the clamshell panel, will forcethe thrust reversing apparatus to its stowed or forward thrust positionin the event of an actuator failure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of ahigh bypass turbofan engine enclosed in a nacelle and mounted on thewing of an aircraft. The thrust reversing elements comprising theclamshell panel of the aft portion of the nacelle, and the ramp panelare shown in their stowed or retracted position;

FIG. 2 is another embodiment of the invention depicting the variableramp exhaust nozzle and clamshell reverser in a round duct exhaustnozzle configuration with a ramp-wedge bifurcation forming it into twoD- shaped nozzles similar to the single one shown in FIG.

FIG. 3 is an enlarged detail view of the preferred embodiment shown inFIG. 1 and depicts the linkage and actuating mechanism with theclamshell panel and blocker door in the thrust reversing position andthe variable ramp, forming the bottom surface of the exhaust nozzle,lowered to the maximum exhaust nozzle area position;

FIG. 4 is a plan view of FIG. 3 with the clamshell panel and blockerdoor in their retracted or nonreversing position;'

FIG. 5 is a rear view of FIG. 3 taken along the line FIG. 6 is a sidesection view taken along line 6-6 of FIG. 5;

FIG. 7 is another embodiment of the invention in a side elevational viewsimilar to FIG. 1 showing a simple link interconnecting the clamshellpanel and the ramp panel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view of apreferred embodiment of the present invention, showing a high bypassratio turbofan engine 20 enclosed in a nacelle 22 which is mountedforward and above on an aircraft wing 24 so that the engine thrust flowis discharged aft over the upper surface of the wing. The wing 24provides a sound deflecting shield against the downward radiation of thesound waves from the engine exhaust nozzle; thereby reducing the groundnoise. The nacelle 22 is mounted on the wing 24 such that its exhaustduct configuration forms a D-shaped exhaust nozzle exit with the uppersurface of the wing. The wall of the nacelle exhaust duct, at its aftend, forms an outer clamshell panel 26 of the thrust reversingapparatus. The clamshell panel 26 is mounted for pivotal rotation aboutan axis 61 transverse to the engine thrust line and adjacent to theupper surface of the wing 24 so that as the clamshell panel 26 pivotsaft from its stowed or retracted position, it leaves an opening in theupper duct wall through which the exhaust flow can be directed;provided, however, that a blocker panel 54 normally stowed downstream ofthe nozzle exit and pivotally mounted adjacent thereto, is rotatedupwardly for flow blockage in combination therewith. The blocker panel54 forms the aft segment of a vertically adjustable three segmentedsurface or variable ramp 30 that forms the lower surface of the exhaustnozzle duct. The operating mechanism of the clamshell panel 26 and thevariable ramp 30 is more clearly shown in the enlarged detail views ofFIGS. 3-6.

FIG. 6 shows the variable ramp 30 connected to structure on the uppersurface of the wing 24 through a linkage support mechanism for raisingand lowering the three segmented ramp. The forward ramp segment 32 ishinged at 34 to fixed wing structure, and supported at its aft end onslide block 36 which is inserted in track fitting 38 mounted to the midramp segment 40. The mid ramp 40 is connected to wing structure througha parallel linkage mechanism comprising: a forward support link 42having one end pivotally connected at 43 to fixed wing structure and theother end pivotally connected at 44 to the forward portion of the midramp 40; and an aft drive link 46 connected at 47 to fixed wingstructure and at 48 to the aft portion of the mid ramp 40. Also, the aftdrive link 46 has an arm 49 pivotally connected at 50 to the rampactuator 52, which in turn is connected to fixed structure at 53. Theaft ramp segment 54 is pivotally supported at 48 on its forward end bythe drive link 46, and at its mid point by a link 56 which through itsinterconnection with the thrust reversing mechanism, swings the aft rampsection 54 up into a flow blockage position to cooperate with theclamshell panel 26 in forming a clamshell blocker door arrangement forreversing the exhaust flow as will more clearly be described infra withreference to FIG. 3. When the ramp linear actuator 52 is in an extendedposition, the three ramp segments 32, 40 and 54 are at their loweredposition as shown in phantom. During low speed flight of the airplane,such as takeoff and landing, or to increase the exhaust nozzle openingfor the sound suppression mode of airplane op eration, the ramp 30 is inits lowered position. During cruise flight speeds of the airplane, theexhaust nozzle exit area is decreased for increased efficiency byretracting the linear ramp actuator 52; thereby, rotating the drive link46 clockwise about the fixed pivotal point 47 and raising the rampsegments. With the trailing edge 55 of the aft ramp segment 54, in itsfully down position a smooth transitional flow over the ramp surfacewith the top surface of the wing 24 is provided for attached exhaustfluid flow when the ramp 30 is in the raised cruise position. When theramp 30 is lowered to its low speed position, the trailing edge 55 islifted off the wing surface or a space is provided therebetween forseparating or unattaching the exhaust fluid flow from the upper surfaceof the wing to improve the acoustic shielding characteristics of thewing. However, if desired and with minor mechanism geometry modification(not shown), the aft ramp trailing edge 55 could also be positionedflush with the upper surface of the wing at the lowered low speedposition of the ramp 30 to permit attached exhaust fluid flow forminimum drag and increased lift from the high velocity exhaust flow overthe upper wing surface.

FIGS. 3, 4, and show in greater detail the reverser mechanism and itsoperation. The reverser is situated in the aft end of the engineoverwing nacelle and comprises a horseshoe or clamshell shaped panel 26which forms the wall and upper structure of the D-shaped exhaust nozzleand duct. The clamshell panel 26 is fixedly mounted on hinge fitting 60which in turn is pivotally mounted for rotation about a fixed structuralaxis 61. The clamshell panel 26 is rotated aft to its thrust revers ingposition by a linear actuator 62 which is connected to fixed structureat 63 and to the clamshell panel 26, at 64. When the linear actuator 62is extended, it swings the clamshell panel 26 aft about its axis 61 andin so doing, rotates a driver arm 66, which is also fixed to theclamshell panel hinge fitting 60, in a clockwise direction when viewedin the side view of FIG. 3. This will induce, through an interconnectinglink 68, a counterclockwise rotation to a first driven arm 70. The arm70 is fixedly mounted on a torque tube 72, which is in parallelalignment with hinge axis 61, and which torque tube 72 is pivotallymounted for rotation about a fixed structural axis 73. Also, fixed totorque tube 72 is a second driven arm 74, which in combination with thefirst driven arm forms a bell crank arrangement. The second driven arm74, is pivotally connected at 64 to one end of the link 56interconnecting the aft ramp segment 54 to rotate it about its forwardpivotal connection 48 in a counter-clockwise direction, as shown in FIG.3, such that the aft ramp segment 54 will swing up into contact with theaft edge of the clamshell panel 26 thereby forming a clamshell blockerdoor for reversing the exhaust flow. Around the inner periphery and atthe forward edge of the clamshell panel 26, is a lip 29, which improvesthe turning action of the exhaust gases to increase the efficiency ofthrust reversal. In a reverse thrust deflector configuration, just byadding a small vane or lip member 29, even though as shown in thefigures as not having much surface, just a few inches makes aconsiderable difference in improving the efficiency of the flow turningeffect.

Referring to FIGS. 3 and 6: the relationship of point 64 (the pivotalconnection between driven link 74 and link 56); and point 65 (thepivotal connection between link 56 and aft ramp segment 54); is suchthat the aft ramp segment 54 will be swung up into contact with theclamshell panel 26 regardless of the operative position of the variableramp 30. Due to the interconnecting linkage mechanism between theclamshell panel 26 and the aft ramp segment 54, as the two surfaces cometogether to form the thrust reversal configuration, the pressure loadsbuild up on the aft ramp segment 54, thereby tending to force thereverser mechanism into the stowed or non-reversing position. This thenprovides for failsafe reverser operation independent of the variableexhaust nozzle area function of the ramp 30, which could be in thecruise or low speed position, or jammed in any position in between. 50that, if the actuation system or the actuators were to lose power, thesurfaces would float back into their forward thrust condition becausethe flap ramp would be a highly loaded surface that would definitelyoverride any loads on the clamshell panel 26 and cause it to tiltforward towards its retracted position. Whereas, if the clamshell panel26 were tilted aft so that it rested entirely onto the upper surface ofthe wing, it would not only be less efficient flow turning geometryarrangement, but also an unsafe reverse thrust condition in that ifactuation power were to be lost, the clamshell panel could not be tiltedforward into the forward thrust condition.

FIG. 2 is another embodiment of the invention wherein the exhaust ductis round and bifurcated by a heat shield 76 and an aerodynamic surface24A, to form two D-shaped exhaust nozzles which are similar inconfiguration to the single one of the preferred embodiment. However,with respect to the actuators, a single actuator 62A could be used forboth of the clamshell panels, as shown in the figure, for synchronizingthe reverser actuation on both sides. Also, in a similar manner (notshown) a single actuator with two links could actuate and synchronizethe variable ramps on the bifurcation planes.

FIG. 7 is another embodiment of the invention which is similar inconfiguration to the previously described preferred embodiment exceptthat the ramp is fixed with the blocker panel 54 pivotally connected at48A to fixed wing structure and the linkage mechanism interconnectingthe clamshell panel 26 with the blocker panel 54 has been simplified tothat of a single link 68A.

While the invention has been described in relation to certainembodiments, it is to be understood that those modifications and changeswhich become obvious to a person of ordinary skill in the art, afterreading the foregoing specification and its teachings, are intended tobe encompassed in the invention disclosed above and limited only by thedefinition of the appended claims.

What is claimed is:

1. Apparatus for varying the exhaust nozzle area and reversing theforward thrust of a jet engine mounted in a nacelle positioned forwardand above on an aircraft wing so as to form a D-shaped exhaust nozzleexit for flow discharge over the upper wing surface comprising: aclamshell panel forming the aft semi-circular portion of the D-shapedexhaust nozzle; a ramp comprising segments forming the flat surface ofthe D-shaped exhaust nozzle fore and aft of the nozzle exit plane overthe upper surface of the wing; means for raising and lowering the rampto vary the exhaust nozzle area; an aft ramp segment rearwardly disposedfrom the exhaust nozzle and being pivotally adjustable to an upwardposition; and means operating independently of the ramp raising andlowering means, for pivoting the clamshell panel aft and downward towardthe upper surface of the wing in combination with raising the aft rampsegment from the upper surface of the wing to an abutment relation withthe clamshell panel to form a clamshell blocker door arrangement forreversing the exhaust flow.

2. The apparatus as set forth in claim 1, comprising: a flow turningvane attached around the periphery of the forward edge of the clamshellpanel to improve the flow turning geometry arrangement and the reversethrust efficiency.

3. The apparatus as set forth in claim 1, comprising: means forpositioning the trailing edge of the aft ramp segment flush with theupper surface of the wing so as to provide a smooth transitional surfacefor attached flow in the high speed cruise operation of the aircraft,and for raising the trailing edge of the aft ramp segment off of theupper surface of the wing so as to provide unattached flow over theupper surfaceof the wing for improving the acoustic shieldingcharacteristics in the low speed takeoff and landing operation of theaircraft.

4. The apparatus as set forth in claim 1, wherein: said ramp segments,when in the lowered position, provide an upper wing surface contourwhich produces a maximum exhaust nozzle area for attenuating the exhaustnoise; and said segments, when in the raised position, produce an upperwing surface contour which substantially reduces the area of the exhaustnozzle for providing acceptable specific fuel consumption and enginecycle requirements at high altitude and high speed cruise mode ofaircraft operation.

1. Apparatus for varying the exhaust nozzle area and reversing theforward thrust of a jet engine mounted in a nacelle positioned forwardand above on an aircraft wing so as to form a D-shaped exhaust nozzleexit for flow discharge over the upper wing surface comprising: aclamshell panel forming the aft semicircular portion of the D-shapedexhaust nozzle; a ramp comprising segments forming the flat surface ofthe D-shaped exhaust nozzle fore and aft of the nozzle exit plane overthe upper surface of the wing; means for raising and lowering the rampto vary the exhaust nozzle area; an aft ramp segment rearwardly disposedfrom the exhaust nozzle and being pivotally adjustable to an upwardposition; and means operating independently of the ramp raising andlowering means, for pivoting the clamshell panel aft and downward towardthe upper surface of the wing in combination with raising the aft rampsegment from the upper surface of the wing to an abutment relation withthe clamshell panel to form a clamshell blocker door arrangement forreversing the exhaust flow.
 2. The apparatus as set forth in claim 1,comprising: a flow turning vane attached around the periphery of theforward edge of the clamshell panel to improve the flow turning geometryarrangement and the reverse thrust efficiency.
 3. The apparatus as setforth in claim 1, comprising: means for positioning the trailing edge ofthe aft ramp segment flush with the upper surface of the wing so as toprovide a smooth transitional surface for attached flow in the highspeed cruise operation of the aircraft, and for raising the trailingedge of the aft ramp segment off of the upper surface of the wing so asto provide unattached flow over the upper surface of the wing forimproving the acoustic shielding characteristics in the low speedtakeoff and landing operation of the aircraft.
 4. The apparatus as setforth in claim 1, wherein: said ramp segments, when in the loweredposition, provide an upper wing surface contour which produces a maximumexhaust nozzle area for attenuating the exhaust noise; and saidsegments, when in the raised position, produce an upper wing surfacecontour which substantially reduces the area of the exhaust nozzle forproviding acceptable specific fuel consumption and engine cyclerequirements at high altitude and high speed cruise mode of aircraftoperation.